Given your intrepid diarist's obsession with the extinction of lumbering organisms who have outlived their usefulness, it was only a matter of time before she was drawn into the hypnotic vortex of Downton Abbey. With the benefit of streaming technology, she has lost countless hours immersed in the dealings of early 20th century aristocrats facing and overcoming truly daunting challenges. One can only marvel at their ability to soldier on, despite having to dress for dinner in black tie, rather than white, or having to cope with the horrific prospect of downsizing to a smaller mansion. Even an unexpected inheritance sends them into multi-episode bouts of self-loathing and handwringing.
Neither hunters nor gatherers and shunning any form of productive activity, these impeccably dressed and coiffed creatures spent their days heaving prolonged sighs of ennui. There's Simply Nothing To Do other than watch as their way of life erodes away beneath them. Having been blessed with Vast Wealth that could have ensured their economic and social dominance for generations more with just a bit of husbandry, they instead frittered it all away through extravagant spending, witless investments, and dereliction of even the most basic fiduciary responsibilities.
No worries, however, as with the miracle of inbreeding, they continued to reproduce with and siphon away the inherited wealth of extended family members. Attempts to deepen their Smurf-deep gene pool by mating with those outside their list of acceptable relatives met with disaster, as we saw when Lady Sibyl - up to then probably the most energetic and genetically robust of the bunch - succumbed to a very dramatic post-partum extinction. The rest of her melanin-deficient clan could only stand by in helpless horror holding the newborn spawn of their former chauffeur. See what happens when the classes mingle? Don't be doing that again, please.
Clearly, though, there were limits to the Downtonasaurs paleo-Ponzi scheme, and eventually, it became painfully apparent even to the most cerebrally-challenged among them that they must adapt to their new circumstances. Not right away, of course, as it was time for another dinner party, wedding, funeral, scandal, fox hunt, or bout of what passes for introspection.
Darwin would have looked upon these socially elevated life-forms with contempt, as they eluded extinction for far too long. Those "below stairs" seemed far better suited for the rough-and-tumble life, as they were only too keen to jostle one another for position, even relying on early forms of social networking and psy-ops. The Dawn of the Age of Mammals might have looked a bit like this. But... I digress.
Where, one wonders, did this whole family begin their march towards irrelevance and extinction? To find the answers, researchers revisited Downton Abbey, this time equipped with a Kubota backhoe, and began the quest for family paterfamilias Cretaceous "Creepy" Crawley. Creepy made his fortunes the old-fashioned way: threatening overextended tenants and driving them off their property, strip mining the available coal and iron ore, selling these important resources in a controlled market to his corporate cronies, and leaving the resultant environmental shambles for future generations to restore.
Having amassed more wealth than he could possibly spend in geologic time, he set about finding a suitable mate. Fortune smiled upon him the day that he laid eyes, and perhaps a bit more, on local barmaid Molly, an opportunistic Mesozoic wench who knew a good meal ticket when she saw one. With her marriage to Creepy, she made the leap to life as Lady Molly Crawley, leaving behind her humble origins. What she lacked in gentility she more than made up for in fecundity, and soon the Crawley cave was alive with the pitter-patter of little Crawley feet.
As time went by, these illustrious offspring went their separate ways. Some of them achieved great distinction in science, medicine, engineering, and the arts. Accordingly, these family members were lopped from the family tree, as that is simply not the sort of lifestyle appropriate for a true aristocrat. After generations of pruning, we find ourselves left with the likes of Robert Crawley, Earl of Grantham, and his emotionally-blocked kin who can wonder for days on end what on Earth they could be doing other than staring into the face of impending ruin. It's all so awfully, awfully tedious, and only by drowning their sorrows in alcohol can they endure their existential pain. Frankly, it's remarkable that they didn't succumb to cirrhosis of the liver, every last one of them.
Just as the real dinosaurs of the Mesozoic must have done, the Crawleys watch, transfixed, as that bright shining ball of flames illuminates their cosmos, getting ever larger. What is that, they wonder. Then, suddenly, it hits them.